We have a big oil problem. As demand for olive oil has soared over the past decade, the trade in the commodity has become unfortunately slippery, says congress chairman Rod Mailer. Shady dealers have been mislabeling and diluting the real thing, and in recent years, Italian authorities have seized thousands of liters of fake or fraudulently labeled oil. The market, alas, may be taking care of the problem. The price of olive oil, which is relatively more expensive than other oils, has slid some 20% this year. The less lucrative it is, the less fraudsters want to fake it. — Genevieve Knapp